JEE Main 2023 Chemistry question

Solid Lead nitrate is dissolved in 1 litre of water. The solution was found to boil at 100.15°C. When 0.2 mol of NaCl is added to the resulting solution, it was observed that the solution froze at –0.8°C. The solubility product of formed is at 298 K. (Nearest integer) Given : = 0.5 K kg and = 1.8 K kg . Assume molality to be equal to molarity in all cases.